Prove that this is true for every n. (n is an element of natural numbers)

cos(n*pi) = (-1)^n

I would very much appreciate your help, thank you.

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- Oct 29th 2012, 11:17 AMjakobjakobsolving trigonometric equation using mathematical induction
Prove that this is true for every n. (n is an element of natural numbers)

cos(n*pi) = (-1)^n

I would very much appreciate your help, thank you. - Oct 29th 2012, 11:31 AMjohnsomeoneRe: solving trigonometric equation using mathematical induction
$\displaystyle \text{Use: } \cos((n+1) \pi ) = \cos(n\pi + \pi) = \cos(n\pi)\cos(\pi) - \sin(n\pi)\sin(\pi), \text{ and continue on from there.}$

- Oct 29th 2012, 12:02 PMjakobjakobRe: solving trigonometric equation using mathematical induction
Thank you for your help.